Water Intoxication: How Much Water Is Too Much?

What Is Water Intoxication?

Before I explain what water intoxication is, here's a short science lesson for you:

When you soak a raisin in water overnight, the raisin swells up and becomes a globe by the next day. Similarly, when you soak a piece of cucumber in concentrated salt solution (pickle water), it shrinks over time and becomes extremely salty to taste.

This process is called osmosis - the property of solvent to move across a semi-permeable membrane from a region of low concentration to high concentration until both compartments (on either side of the barrier) are in equilibrium.

In simpler terms, it means when you drink too much water, it dilutes your blood's sodium concentration compared to its concentration within the cells of your body. This causes water to rush into your cells, causing them to burst open and lead to life-threatening consequences, especially in your brain.

This is known as water intoxication (or water poisoning).

Signs And Symptoms Of Water Poisoning

When water intoxication causes your brain cells to swell up, they press against the inner surface of your skull, leading to excruciating headaches, nausea, and vomiting.

Other symptoms include high blood pressure, double vision, tremors and weakness in muscles, and difficulty in breathing.

In fact, if the water intoxication is too much, it can even lead to coma and death. And the people most at risk of dying because of this are soldiers and athletes whose symptoms of water poisoning are often confused with dehydration, thus causing their death after excessive efforts to "rehydrate" them.

How Much Water Is Too Much?

That depends on two factors: the filtration capacity of your kidneys and the duration of time during which you had it.

First up, healthy human kidneys are capable of filtering out upto 1 L of water every hour. So if you end up drinking more than that, that increases your risk of water intoxication. And this risk is higher for those with chronic kidney disease or with just one functional kidney.

Also, the duration of time matters a lot. For example, drinking 10-20 L of water within a few hours increases your risk of water intoxication drastically. But doing the same over a period of 24 hours does not.

How Much Water Should I Drink, Then?

This question does not have a one-size-fits-all answer. Instead, the amount of water you should drink every day depends completely on your physique, your unique medical condition, and your exertion level.

But if you want an average range, men should drink 3.7 L of water every day and women should have 2.7 L.